In principle, an implant means a substitute configured to restore damaged human tissue. However, in dentistry, an implant means a series of medical procedures for implanting an artificial tooth. In the medical procedures, a fixture, which is a dental root formed of such rejection-free material as titanium to replace a damaged dental root, is implanted into an alveolar bone where a tooth was pulled out, and then a dental implant is fixed to restore functions of the tooth.
Typical prostheses or dentures may hurt adjacent teeth and bones with time. However, an implant does not hurt adjacent tooth tissue, and may be used semi-permanently since it causes no tooth decay while having the same function and shape as a natural tooth.
In the medical procedures, also referred to as an implant or implant procedures, a designated drill is used to bore a hole at an implant location, and then a fixture is implanted into and osteointegrated with an alveolar bone, although the procedures may be different depending upon a variety of types of the fixture. Then, in general, an abutment is coupled with the fixture, and a finishing prosthesis is applied to the abutment to finish the procedures.
An implant may restore a single missing tooth, increase the functions of the dentures of a patient with partial or complete anodontia, improve the appearance of a dental prosthesis, disperse the excessive stress upon adjacent supporting bone tissue, and help stabilize a set of teeth.
In general, such an implant includes a fixture which is an artificial dental root to be implanted, an abutment coupled with the fixture, an abutment screw fixing the abutment to the fixture, and an artificial tooth coupled with the abutment. Here, a healing abutment (not shown) may be coupled with the fixture to maintain the coupled state before the abutment is coupled with the fixture, i.e., until the fixture is osteointegrated with an alveolar bone.
A fixture, which is a part of an implant, is implanted into a drilled hole in an alveolar bone where the medical procedures are to be applied, and acts as an artificial dental root. Therefore, a fixture needs to be firmly implanted in the alveolar bone.
Thus, a thread part (thread) may be disposed on the outer surface of a fixture so that the fixture is firmly coupled with the inner sidewall of an alveolar bone where a drilled hole is formed. The thread part is led into the alveolar bone so that the fixture and the alveolar bone are firmly coupled with each other, and strengthens the force with which the fixture fixes the alveolar bone by increasing the contact area of both.
Meanwhile, as described above, an implant surgery is carried out by forming a hole with a drill in an alveolar bone, implanting a fixture in the hole, coupling the fixture with an abutment when osteointegration progresses, and then applying an artificial tooth to finish the procedures. In such an implant surgery, fixtures with different sizes (maximum thread diameters) may be used depending upon operation conditions. Then, different drills need to be used. Usually, a large-scale drill is used for a large fixture, and a small-scale drill is used for a small fixture since the bodies of the fixtures vary depending on the sizes of the fixtures.
However, a cumbersome operation may be entailed when a drill corresponding to the size of a fixture needs to be selected, or when an additional boring is required for implanting a larger fixture with a hole for fixture implanting already formed in an alveolar bone. Especially, when another fixture is implanted after an initial implanting failed, an additional boring with an additional drill is necessary since the sizes of the bodies of the fixtures are different. Therefore, the development of a new implant system is required for more convenient implant procedures.
On the other hand, in a typical conventional dental implant fixture, a certain section of a thread part is discontinued, that is, the thread part does not continue, and a cutting edge portion is formed in the discontinued area to make a fixture easily implanted. However, the cutting edge portion formed by discontinuing the thread part may misalign the fixture with a desired implantation direction and thus a solution for this issue is needed.
Also, in the conventional dental implant fixture, since the thread part is formed across the entire area of an outer surface of a body of the fixture, when an entrance of a hole is relatively narrow, for example, a bone (an alveolar bone) existing in an opening area of the hole may be damaged due to the thread part formed in the entire area of the outer surface of the body. As a result, an implant surgery may fail and thus a solution for this issue is needed.